"It will take a lot of research, and a lot of time, but there are also a lot of commercial applications, not just military applications," he says.

The idea of communicating by thought alone is not a new one. In the 1960s, a researcher strapped an EEG to his head and, with some training, could stop and start his brain's alpha waves to compose Morse code messages.

The army grant has two objectives.

The first is to compose a message using, as D'Zmura puts it, "that little voice in your head".

The second part is to send that message to a particular individual or object (like a radio), also just with the power of thought. Once the message reaches the recipient, it could be read as text or as a voice mail.

While the money may come from the army and its first use could be for covert operations, D'Zmura thinks thought-based communication will find more use in the civilian realm.

Part of a hat

EEG-based gaming devices are large and fairly conspicuous, but D'Zmura thinks that eventually they could be incorporated into a baseball hat or a hood.

Another use for such a system is for patients with Lou Gehrig's disease, or ALS.

As the disease progresses, patients have fully functional brains but slowly lose control over their muscles. Synthetic telepathy could be a way for these patients to communicate.

One of the first areas for thought-based communication is in the gaming world, says Biomedical Engineering Associate Professor Paul Sajda of Columbia University.

One difficulty in composing specific messages is fundamental: EEGs are not very specific.

They can only locate a signal to within about one to two centimetres. That's a large distance in the brain.

Invasive surgery

In the brain's auditory cortex, for example, two centimetres is the difference between low notes and high notes, D'Zmura says.

Placing electrodes between the skull and the brain would offer more precise readings, but it is expensive and requires invasive surgery.

To work around this problem, the scientists need to gain a much better understanding of what words and phrases light up what brain sections.

To create a detailed map of the brain scientists will also use functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG).

Each technology has its own strengths and weaknesses.

EEGs detect brain activity only on the outer bulges of the brain's folds. MEGs read brain activity on the inner folds but are too large to put on your head. FMRIs detect brain activity more accurately than either but are heavy and expensive.

Of all three technologies EEG is the one currently cheap enough, light enough and fast enough for a mass market device.

The map generated by all three technologies will help the computer guess which word of phrase a person means when a part of the brain lights up on the EEG.

Mapping the brain's response to most of the English language is a large task, and D'Zmura says that it will be 15-20 years before thought-based communication is a reality.

'Technical hurdles'

"There are technical hurdles that need to be overcome first, but then again, 20 years ago people would have thought that the two of us talking to each other half a world away over Skype (an internet-based phone service) was crazy," says Sajda.

To those who might be nervous about thought-based communication turning into a sci-fi comedy of errors, D'Zmura says not to worry.

Mind-message composition would take specific conscious thoughts and training to develop them. The device would also have a on/off switch.

"When I was a kid I occasionally said things that were inappropriate, and I learned not to do that," says D'Zmura.

"I think that people would learn to think in a way the computer couldn't interpret. Or they can just switch it off."